Location: Livestock Nutrient Management Research2010 Annual Report
1a. Objectives (from AD-416)
To determine, in cooperation with scientists from Texas AgriLife Research, Kansas State University (KSU), Texas A&M University (TAMU), and West Texas A&M University (WTAMU), atmospheric ammonia and methane concentrations and emissions at commercial beef cattle feedyards and to determine the effects of environmental and management factors on these emissions.
1b. Approach (from AD-416)
Ammonia emissions will be measured at two commercial beef cattle feedyards in Texas using open path lasers and a backward Lagrangian Stochastic model. Methane emissions will be measured from the retention pond and pen areas of one commercial feedyard using the same methodologies. Nitrogen and carbon balance will be determined based on chemical composition of diets, fresh feces, aged manure, and animal weight gain. Effects of environmental factors, pond chemistry, pen surface chemistry, and management factors on emissions will be monitored. A respiration calorimetry system will be constructed to measure enteric and metabolic methane, carbon dioxide, ammonia and hydrogen sulfide flux from cattle. These data have value for development, improvement, and/or verification for statistical and process-based models of ammonia and methane emissions. Potential methods to decrease ammonia emission will be studied using lab-scale and small plot-scale studies. Ammonia emissions from pen surfaces treated with varying chemicals will be measured using flow through lab chambers or a static chamber on feedlot plots.
3. Progress Report
This project is a continuation of project 6209-31630-002-28R (Ammonia and methane emissions in beef cattle feedyards: Federal Air Quality Initiative, Agreement 58-6209-8-049). Accurate estimates of ammonia emissions from beef cattle feedyards are needed as regulatory requirements and the need for accurate emissions inventories increase. ARS researchers from the Conservation and Production Research Laboratory, Bushland, Texas, almost continuously measured ammonia and methane emissions at two commercial feedyards using open path lasers and an inverse dispersion model. Monthly ammonia-nitrogen loss, as a fraction of fed nitrogen, agreed with our previous results. The fractional loss and per capita emissions during winter months was approximately 50% of losses during summer months. These measured losses were substantiated using total nitrogen balance. Feeding distiller's grains at one feedyard increased the crude protein content of the diet from 13% to 19%, and also increased the average monthly ammonia emissions by 44% to 144%, compared with the feedyard with corn-based rations. Methane concentrations and fluctuations were measured at one feedyard for 12 months. Preliminary data indicated that the diel methane concentration over the retention pond was bimodal, with peaks at pre-dawn and pre-midnight. Daily summertime methane emission rates were lower during the early morning and daytime and increased during the early nighttime. Four open circuit, indirect respiration calorimeters were constructed, tested, and validated in order to perform several studies that are currently in progress. These studies are to determine the effects of corn processing method and feeding of wet distiller's grain on enteric methane and hydrogen sulfide losses and nitrogen excretion of cattle fed high concentrate finishing diets. Quantifying the variability of ammonia and methane emission rates and the impact of factors that affect them will yield databases for scientists to validate and verify process models of emissions, provide the cattle industry with accurate science-based emissions data to meet regulatory requirements, and give regulators more accurate, comprehensive data from which to build emissions inventories. A series of symposia were held on August 24-26, 2010, at two locations in Texas and one in Kansas to disperse research results to cattle producers, consultants, and Natural Resouces Conservation Service representatives.